Stoking mechanism



june 17,1924,

J. G. woRKER STOKING MECHANISM Filed Oct. 3o 1920 2 sheets-sheet .1,

IN VEN TOR.

W I TNESSES: @www ATTOREY l l june 17 '1924.

Filed oct. 3o.

ATTORNEY Patented .lime 7, 1924.',

NrrED TES JOSEPH Gr. WORKER, OF EAU CLAIRE, WISCONSIN.

STOKING MEGEANISM.

Application filed October 30, 1920. Serial No. 420,663.

To all whom t may concern:

Be it known that I, JOSEPH G. WORKER,y

acitizen of the United States, and a resident of Eau Claire` in thecounty of Eau Claire and State of lVisconsin, have invented a. new anduseful Improvement in Stoking Mechanism, of which the following is aspecification.

This invention relatesto stokers and particularly to that class ofstokers known as :mtomatic stokers commonly used in heating steamboilers. Such stokcrs usually comprise an inclined combustion gratesupplied with fuel at the front end either by overfeed or underfeedmechanism or both, the combustion grate beingusually supplemented by apivoted diunp grate closing the dumping opening at the lower and rearend of the grate between the lower end of the combustion grate and thecustomary bridge wall of the furnace.

In the usual type of furnace the mixture of ashes and slag accumulatingower the dump grate adheres firmly to thebridge wall. This accumulationinterferes with` the proper operation of the'dump grate and thecombustion of the fuel at the rear of the furnace and must therefore bedislodged at quite frequent intervals. The slag adheres !'irmly andoccasions much difficulty in its removal, necessitating severemanipulation with a heavy iron rod or paddle. The frequency and severityof the operation does appreciable damage to the bridge wallnecessitating expensive repairs thereof which occasion costly delays inthe operation of the plant.

The principal objects of this invention are the production of a stokingmechanism in which the accumulation of slag adjacent the bridge wall issubstantially prevented; the production of a stoking mechanism whereinthe fuel usually wasted at the rear end of the furnace is burned; theproduction of a stoking mechanism wherein the fuel is properlymanipulated automatically so as to cause complete combustion of the fuelwith a minimum production of slag; the production of an automaticstoking mechanism that requires comparatively little manu'al labor inkeeping the ash discharge open and free from sla-g accumulation; theproduction of an improved dump grate mechanism whereby combustion isfacilitated at the rear of the furnace; the production of an improveddump grate which is substantially self-cleaning and thereforepractically free of slag deposits; the production of.

means in connection with a dump grate for preventing burning of thegrate, and suchv other objects as may hereinafter appear. Certainembodiments of the invention are *illustrated in the accompanyingdrawings "-wherein Fig. 1 is a partial plan view in part dia.- grammaticof the rear end o-f a furnace showing the improved dump grate mecha-'nism with portions shown in horizontal section;

Fig. 2 is a vertical section in part diagrammatic through a furnace online II--II of; Fig. 1;

F ig. 3 is an enlarged vertical section showing grate operatingmechanism; and

Fig. -1 is an end view of a valve used in connection withthe'cylindrical dump grate.

This invention relates particularly to dump grate mechanism used inconnection with a well known type of underfeed automatic Stoker. Such astoking mechanism is illustrated in F ig. 2, wherein the fuel is fedinto a hopper 1 and is passed into a furnace through a passage 2 bymeans of a reciprocating plunger 3 operated by a motor 4 whichcontinuously rotates a shaft 5 and with it a crank 6.' The plunger 3 isconnected to the crank 6 by means of a link 7 which reciprocates theplunger back and forth at each revolution of the shaft 5.

After passing through the passage 2, thev fuel enters a number of fueltroughs 8 ar- -ranged in parallel relation with tuyre boxes 9 betweenthem. The coal is therefore fed from beneath the burning surface, yandair is supplied tothe fuel bedI through the openings in the tuyere boxescommunicating with a wind box 10 arranged beneath the grateconstruction. The wind box l0 is supplied with a blast of air through apair of verticallydisposed conduits 10a (Figs. 1 and 2). The grate4mechanism just described is usually supplemented by a moving grate 11which, v in some furnace constructions, is adapted to' bey reciprocatedfrom and toward the l tuyre boxes by lany suitable mechanism operated bythe motor shaft 5. The air supplied to the grates just described iscontrolled by butterfly valves l2 arranged in various places in the windbox 10.

At the rear end of the furnace, a bridge wall 13 is separated fromtherear end of the movin grate 11 so as to provide a refuse pit orumping opening 14 between the moving grate and the bridge wall throu hwhich ashes and other residue from the uel may bel discharged. In therefuse pit 14, a plurality of cylindrical dump grates 15 are dis posedlongitudinally thereof and are preferably situated beneath and at therear of the rearmost active grate 11 so as to receive the materialdischarged therefrom. These cylindrical grates are closed at their endsYand are pivoted for rotation upon a hollow trunnion shaft 16 extendingentirely across the Width of the furnace or transverse to the directionof flow of the fuel. The trunnionshaftc 16 is mounted inl hollowbearings 17 and, 1s provided with two sets of perforatlons 18 and 19,the former beingv disposed so as to discharge into -the interior of thecylindrical grates 15, and,the latterl per` forations are adapted tocommunicate with chambers 20 in the hollow bearings 17 so that airsupplied to the bearing chamber 20 through the pipe 21 may enter theinterior of the trunnion anddischarge through the openings 18 or fromthe other end of the trunnion into the chamber 20 and out through theconduit 2.2. The purpose 'of such circulation of air through thetrunnion shaft 'will .hereinafter appear.

The cylindrical dump grates 15 are hollow, the c lindrical shellsthereof being pro# vided wit ports or perforations 23 through which airsupplied lto the interior of the `dump grates' may be discharged in tocontact with the material supported upon the cylindrical dump grates 15.It isthe object of these perforations to supply a blast of air tothe ashdeposited on the upper surface of the dump grate. In order to economizethe air and sup ly itonly to that por-Y tion of the surface o thecylinder in contact with the ash, the interior of the cylindrical dumpgrate is provided with asegmental cylindrlcal valve 24 carried upon thetrunnionvshaftl 16 by means of bearings-or webs 25 integral with orsecured to theA valve 24. .An end view of this valve is illustrated inFig. .4 which shows that the cylindrical portion thereof extends throughan arc of morev than ,180 and as shown in Fig. 2 prevents the escape ofair `through any perforations 23 except those between the points a and bwhich are uncovered by thevalve.l It will be seen that i'f'the valv324is held stationary and the dump grate 15 rotated, the ports`23 locatedaround the perforations of the dump grate will be successively opened atthe point *a and closed at the point b so that air only escapes throughthe points of the cylinder in contact with the mixture of `fuel andashes. By reason of the blast of air which f may pass through theperforations any combusti le naterial remaining in the ashes will beconsumed. v v

The trunnion shaft 16 is 4supported upon rocker arms 27 which are-keye28 extendin parallel with the dump grate, this shaft emg mounted forrotationin. suitable` bearings 29 carried lupon I-beams 30 which beamsserve to support the rear end of the furnace structure.- The shaft 28 isadapted to berocked or oscillated by end of the furnace where' itisprovided with a hand wheel' (not/shovim)l whereby the worm 32 maybemanipulated. e When it is desired to dumpthe grate, the worm 32 isactuated vso as to move the worm-.gear 31 counterclockwise, which actionwill lower the trunto a shaft means of aworm gear segment 31 which ismeshed with a worm 32 leading to the front nion shaft 16 and with it thedump grateso' ffas to dump the furnace whenever itis desired. 'It willbe seen that by this mechanism the relative position o'f the dump gratewith respectv to the moving grate 11 can be r -which extends forwardlyof theJfurnaoe and is pivotally connectedto a bell crank leverl 37pivotally carried by a-bracket 38 secured of the furnace. The forwardarm of the rocking lever 37 is pivotally connected to a yielding linkconnection 40 which is pivoted at its upper end to the crank 6, operatedby the motor 4. The yielding connection 40 may be of any ,suitableconstruction and as shown consists of telescoping members 44 and '45 anda spring 46subject to compression upon the imposition thereon of a loadgreaterv than a predetermined `safe load. The link 36 is supportedbetween thev bell crank 37 and the rocking lever 35'v by means of a link41. It will be seen from the foregoingthat, for each revolution ofthecrank 6, the rocking lever 35 will; be oscillated back and forth onceand with each oscillation the weighted pawl 34 willratchet over certaindump grate 15 will be intermittent y rotated counterclockwise.

The rotation of the Idump grate intermittently toward the bridge 4wallcauses the ash -to the I-beam 39 supporting the frontend teeth of theratchet wheel 33 so that for each oscillation of the lever 35 the clindrical ias tobe agitated and movedtoward the bridge.'

:wall and finallyfdischarged into the ash pit beneath the dumpmg grate.Any clinkers toolarge to normally pass over the dump "subsequentlythrough the cylindrical grates 15. Any excess of air is returned to thewind box 10 through the conduits 22, previously 'referred to. Thiscirculation of air prevents any overheating of the trunnion shaft andthe cylindrical dump grate 15 and therefore the dump grates are notliable to be burned out.

The trunnion shaft 16 is preferably rotatable in bearings 17, and thebearings of the valves 24 preferably have loose fitting collars 42embracing the trunnion shaft 16. llt is also desirable to provide thevalves 24 with counterweights 43 (Fig. 4) so that they may be held bygravity in the position i1- lustrated in Figs. 2 and 3.

While I have shown my invention in two forms, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various other changes and modifications without departing from thespirit thereof, and' 1 desire, therefore, that only such limitation`shall be placed thereupon as are imposed by the prior art or as arespecifically set forth in the appended claims.

1What I claim is 1. A dump grate for stoking mechanism comprising amoving hollow grate member provided with ports for the passage of fluidthrough the member into contact with the material on the surfacethereof, and a valve closing such ports as do not discharge into contactwith said material.

2. A dump grate for stoking mechanism comprising a moving hollow gratemember having a single chamber provided with ports extending through theshell of the member exposed to contact with combustible materials andcommunicating with the interior of the grate member, means for supplyingfluid to the interior of the grate member, and means closing such portsas do not discharge into contact with said niaterial. l

3. The combination with a stoking mechanism of a combustion grate, arefuse pit at the rear of the combustion grate, a moving hollow dumpgrate adjacent to the combustion grate and adapted to receive and toconvey material discharged from the combustion grate, said hollow dumpgrate having ports for delivering fluid to the material supportedthereon, means for intermittently moving the dump grate, and meansclosing such ports as do not discharge into contact with the materialduring the movement of the dump grate. 4. The combination with a stokingmechanismhaving a combustion gra-te terminating adjacent a dumpingopening, of a rotary1 dump grate in said opening adjacent to saidcombustion grate, means for actuating said dump grate for elfectingl anintermittent movement of the ash-supporting surface contiguous to theplane of the combustion grate, and means for bodily moving the dumpgrate substantially transversely to the' plane of the combustion grate.

5. A stoking mechanism comprising in combination, a combustion grate,afstop member spaced from the discharge end of the combustion grate toform a dumping opening, a cylindrical dump grate in the opening, meansfor rotatingthe dumping grate so as to convey material from thecombustion grate and crush it downwardly between the stop member and thedumping grate, and means for bodily swinging said cylindrical dumpinggrate downward y out lof the path of the material passing through thedumping opening,

6. A stoking mechanism comprising in combination, a combustion grate, astop member spaced from the discharge end of the grate t0 form a dumpingopening, a cylindrical dump grate in said opening adjacent to thecombustion grate, spaced from the stop member and adapted to receive ashdischarged from the combustion grate, means for rotating the dumpinggrate to move ash toward said sto-p member, and means for bodilyadjusting the position of the dump grate with respect to the stopmember.

7. A dump grate for a stoking mechanism comprising a rotary hollowcylinder, means for supplying fiuid to the interior of the cylinder, theshell of the cylinder having ports for the discharge of fluidtherethrough, and a valve for closing certain of said ports, so as tosecure uniform directional discharge through the open ports during therotation of the hollow cylinder.

8. A dump grate for stoking mechanism comprising a rotary hollowcylinder, means for supplying fluid to the interior of the cylinder. theshell of the cylinder having ports for the discharge of fluid in thecylinder through the grate 'surface thereof, and valve means closingeach 'of the ports duringl a predetermined arcuate travel of therotating cylinder.

9. Stoking mechanism comprising in combination, a combustion grate,means for feeding fuel to the grate, means for operating the fuelfeeding means, a hollow rotary dumpgrate cooperating with the combustiongrate, means for rotating the dump grate actuated bvthe said operatingmeans, said hollow dump grate having ports for the delivery of fluid tothe material-passingv ing aim to'the interior of the dump grate from thesaid air supply passage, and means for discharging air from the` dumpgrate into the said @wind box.

combination a combustion grate discharging v into a refuse pit, a stopmember spaced from the discharge end of the combustion grate so as toprovide a dump opening into the refuse pit, a rotary dump grate at oneside 13. A dump grate for fuel stoking mecha. ni'sm, comprising a hollowperforated trun'- nion shaft, a rotar hollow dump grate supported insaid sha t and having ports in the portion of the shell thereof incontact with the combustible fuel, a valve carried by' the;

trunnion for closing certain ports in the dump grate shell, and meansfor holding the valve in a predetermined positione 14. A dump grate fora stoker comprising 11. Stoking mechanism comprising in; a hollowcylinder having peripherally discombination, a combustion grate, a windbox posed ports, means for supplying fluid to for supplying air to therate, an air supply the hollow cylinder, means for rotating the passageleading to the windbox, a hollow` cylinder, a segmental cylindricalmember dump grate cooperating with the combusdisposed within the hollowcylinder and artion grate, means connecting the interior of ranged toclose ports which in the rotation the vdump grate with the said. airsupply pasof the hollow cylinder are not in a position sage and`meansconnecting the interior of Jto discharge fluid into contact with themathe dump grate with the wind box whereby terial supported by thehollow cylinder. air may passv from. the supply passage In testimonywhereof, I have hereunto through the dump grate and into the saidsubscribed my name this twenty-fifth day of wind box. p October, 1920.

'12. Stoker mechanism comprising 7in JOSEPH G. WORKER.

